/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.http.server;

import org.springframework.util.MultiValueMap;

import java.util.List;

/**
 * Structured representation of a URI path whose elements have been pre-parsed
 * into a sequence of {@link Separator Separator} and {@link PathSegment
 * PathSegment} elements.
 *
 * <p>An instance of this class can be created via {@link #parsePath(String)}.
 * Each {@link PathSegment PathSegment} exposes its structure decoded
 * safely without the risk of encoded reserved characters altering the path or
 * segment structure and without path parameters for path matching purposes.
 *
 * @author Rossen Stoyanchev
 * @since 5.0
 */
public interface PathContainer {

    /**
     * Parse the path value into a sequence of {@link Separator Separator} and
     * {@link PathSegment PathSegment} elements.
     *
     * @param path the encoded, raw URL path value to parse
     * @return the parsed path
     */
    static PathContainer parsePath(String path) {
        return DefaultPathContainer.createFromUrlPath(path);
    }

    /**
     * The original path that was parsed.
     */
    String value();

    /**
     * The list of path elements, either {@link Separator} or {@link PathSegment}.
     */
    List<Element> elements();

    /**
     * Extract a sub-path from the given offset into the elements list.
     *
     * @param index the start element index (inclusive)
     * @return the sub-path
     */
    default PathContainer subPath(int index) {
        return subPath(index, elements().size());
    }

    /**
     * Extract a sub-path from the given start offset (inclusive) into the
     * element list and to the end offset (exclusive).
     *
     * @param startIndex the start element index (inclusive)
     * @param endIndex   the end element index (exclusive)
     * @return the sub-path
     */
    default PathContainer subPath(int startIndex, int endIndex) {
        return DefaultPathContainer.subPath(this, startIndex, endIndex);
    }


    /**
     * Common representation of a path element, e.g. separator or segment.
     */
    interface Element {

        /**
         * Return the original, raw (encoded) value for the path component.
         */
        String value();
    }


    /**
     * Path separator element.
     */
    interface Separator extends Element {
    }


    /**
     * Path segment element.
     */
    interface PathSegment extends Element {

        /**
         * Return the path segment value to use for pattern matching purposes.
         * By default this is the same as {@link #value()} but may also differ
         * in sub-interfaces (e.g. decoded, sanitized, etc.).
         */
        String valueToMatch();

        /**
         * The same as {@link #valueToMatch()} but as a {@code char[]}.
         */
        char[] valueToMatchAsChars();

        /**
         * Path parameters parsed from the path segment.
         */
        MultiValueMap<String, String> parameters();
    }

}
